Submerged oil well plunger pumps of the displacement type consist of a plunger and traveling valve reciprocatingly received within a stationary working barrel. The working barrel is provided with a standing valve and is submerged in well fluid and sometimes removably attached to tubing extending to the surface. Reciprocal motion is induced into the traveling valve by a pumpjack by means of a sucker rod string. Sometimes the pump is anchored within the tubing string by special seating attachments engaging suitable shoes disposed on the bottom part of the tubing string thereby enabling removal of the pump by means of the sucker rod rather than having to pull the entire tubing.
The pump plunger of the prior art is provided with various cups and steel followers for effecting the necessary fluid seal between the plunger and working barrel. The specific arrangement of the plunger, tubing, working barrel, valves, and various seals enable the downhole pump assembly to be classified as stationary working barrel, plunger insert, stuffing box plunger insert, inverted plunger or traveling outer tube, and the fluid packed pump assembly.
The present invention relates to improvements in the plunger of a submerged oil well plunger pump and for purpose of illustration, is shown associated with a stationary working barrel.
In the prior art plunger pumps, the seal between the plunger and the working barrel looses its close tolerance fit because of wear which occurs therebetween.
Accordingly, it is desirable to provide the traveling plunger of a downhole submerged pump with means by which the exterior of the plunger is sealed to the interior of the working barrel with the seal being expanded by means of fluid pressure effected within the working barrel, thereby overcoming some of the loss in efficiency generally associated with improper clearance between the wearing surfaces of the plunger and barrel.